A former mayor of Detroit was convicted of corruption charges on Monday, ensuring a return to prison for a man once among the nation's youngest big-city leaders.

Jurors convicted Kwame Kilpatrick of a raft of crimes, including racketeering conspiracy, which carries a maximum punishment of 20 years in jail. He was portrayed during a five-month trial as an unscrupulous politician who took bribes, rigged contracts and lived far beyond his means while in office until the fall of 2008.

Kilpatrick wore a surprised look at times as US district judge Nancy Edmunds read the jury's verdict: guilty of 24 charges, not guilty on three and no consensus on three more. Kilpatrick declined to speak to reporters as he left the courthouse.

Prosecutors said Kilpatrick ran a "private profit machine" out of Detroit's city hall. The government presented evidence to show he got a share of the spoils after ensuring that ab excavating company was awarded millions in work from the water department.

Business owners said they were forced to hire Bobby Ferguson as a subcontractor or risk losing city contracts. Separately, fundraiser Emma Bell said she gave Kilpatrick more than $200,000 as his personal cut of political donations, pulling cash from her bra during private meetings. A high-ranking aide, Derrick Miller, told jurors that he often was the middle man, passing bribes from others.

Ferguson, a friend of Kilpatrick, was also convicted of racketeering conspiracy. The jury could not reach a verdict on the same charge for Kilpatrick's father, Bernard Kilpatrick, but convicted him of submitting a false tax return.

The judge said the jury finished its work Friday but wanted to go home for the weekend before announcing the results Monday.

"They said they wanted to sleep on it … I had a sense of what the verdict was," Edmunds told reporters.

Kilpatrick, who now lives near Dallas, declined to testify. He has long denied any wrongdoing, and defense attorney James Thomas told jurors that his client often was showered with cash gifts from city workers and political supporters during holidays and birthdays.

The government said Kilpatrick abused the civic fund, a nonprofit fund he created to help distressed Detroit residents. There was evidence that it was used for yoga lessons, camps for his children, golf clubs and travel.

"The scale of corruption was breathtaking," assistant US attorney Mark Chutkow said in a closing argument on 15 February. "We cannot turn away and ignore the corruption that occurred in this city. It is time for the former mayor and his accomplices to be held accountable for their crimes – it is past time."

The current mayor, Dave Bing, said the verdict would allow the city to move on from "this negative chapter in Detroit's history".

In a statement Monday, he said it was "time for all of us to move forward with a renewed commitment to transparency and high ethical standards in our city government".

Kilpatrick, 42, was elected in 2001 at age 31. He resigned in 2008 and pleaded guilty to obstruction of justice in a different scandal involving sexually explicit text messages and an extramarital affair with his chief of staff.

The Democrat spent 14 months in prison for violating probation in that case after a judge said he failed to report assets that could be put toward his $1m restitution to Detroit.

Voters booted his mother, Carolyn Cheeks Kilpatrick, from Congress in 2010, partly because of a negative perception of her due to her son's troubles.